This invention relates to an apparatus and a method for producing a sand mold, in particular, to an apparatus and a method for producing a sand mold wherein both introducing molding sand into a mold space and compacting the introduced molding sand are performed at one station.
In a conventional method of producing a sand mold by a mold-producing installation wherein both molding and teeming are performed while a sand mold is being held in a flask, it is known that introducing molding sand into a flask and compacting the introduced molding sand are performed in two different stations, which are spaced apart from each other (for example, JP 3-35842, A). Since both introducing molding sand into a flask and compacting molding sand introduced into another flask are simultaneously performed at that installation, sand molds are produced at a high rate. However, the installation requires both a molding-sand introducing station and a molding-sand compacting station, and further, requires more time and energy to transfer flasks between the two stations. Further, a molding machine must be provided with transfer equipment. For these reasons, a problem is caused in that the molding machine is complicated and expensive.
In another conventional method of producing a sand mold, wherein both the introduction and compaction of molding sand is performed in a single station, a ram must be horizontally moved above a mold space to compact the molding sand that has been introduced into the mold space. This also requires installing transfer equipment. Thus the same problem is caused, in that the molding machine is complicated and expensive.
The purpose of the present invention is to resolve those problems and to provide an apparatus and a method for producing sand molds wherein the cycle of producing them is shortened, and energy consumption is reduced.
In one aspect of the apparatus of the present invention for producing a sand mold, a plurality of nozzles are mounted on a lower portion of a sand hopper that contains molding sand, and a plurality of squeeze feet, the pressure of which is controlled, are mounted on the lower portion of the sand hopper at locations adjacent to a side of each nozzle. The sand hopper is supported by supporting means in such a manner that it can move vertically. A pattern plate having a pattern, a flask, a filling frame, and the sand hopper having the squeeze feet that are disposed above the filling frame all define a mold space. The molding sand in the sand hopper is introduced into the mold space by discharging it from the nozzles of the sand hopper, and the molding sand in the mold space is compacted by the squeeze feet when the sand hopper is lowered to the mold space. In the molding machine so arranged, both introducing molding sand into the mold space and compacting the molding sand in the mold space are performed at one station (a molding-sand introducing and compacting station). Thus the purpose of the invention is achieved.
In an example of the aspect, the supporting means hold the flask so that it moves vertically.
In an example of the aspect, either the supporting means or the sand hopper holds the filling frame so that it moves vertically relative to the sand hopper.
In both examples the molding space is readily defined, and the filling frame can be positioned at the level of a pass line (a transfer passage for flasks) that passes through the molding-sand introducing and compacting station of the molding machine.